Draft gear



April 28, 1953 J. R. CARDWELI.

DRAFT GEAR s sheets-sheet 1 original Filed May 12, 1948 April 28, 1953 J. R. cARDwELL 2,636,620

DRAFT GEAR Original Filed May l2, 1948 April 28, 1953 J. R. CARDWELL. 2,636,620

DRAFT GEAR original Filed May 1'2, 194s s sheets-sheet s Patented Apr. 28, 195.3

DRAF T GEAR James R, `lardwell', Barrington, Ill., ass'gnor to Cardwell Westinghouse Company; a corpora.-

tonof Delaware @riginal application May 12, 19485` Serial No.`

3' Claims.

My invention relates to friction draft gears` for railway oars and the` principal object of the invention is toprov-ide a gear of this type that is characterized by compactness, high capacity, and yet softness of' action particularlyduring the preliminary travel of thegear;

Further and other objects of the invention will bec-ome apparent as the disclosure proceeds, and the description is read inv conjunction with the accompanying drawings in which:

Figure 1 is a longitudinal sectional4 View through a draft gear built` in accordance with this invention Figure 2 is an end View ofthe gear with'parts broken away;

Figure 3` is a faceview, orviewI in ehr/ation,` of the cluster of" wedge members employed in the draft gear;

Figure 4 is a fragmentary@viewfoorresponding to Figure 1', but show-ingthe draft gear` afterthe preliminar-y travel, orpartly compressed;

Figure 5 is an emilodedV viewA of" the parts` as sembledin Figure 1 and..`

Figure: (this a: diagrami comparingfthe Charade teristic curve of a` high*` compression draft gear: with thecurve of the draftgearshowininllliguresL l to 5, inclusive;`

This applicationv isat,divisionor?V my eariierapfplication, Serial"Nad/iilt.llediMay l2, ma; which .has now maturedintd Restent; No;` 2,'fi96ti42.; granted February lg n laat; andithe;` disclosure oisuch patent` is hereby incorporatedinztotoin the; present, application with the reference: charia Divided and this application May 7,

ters denoting the salnefnarts; n in application: as: in the. heretofioreiderltirlediA natented dise` closure;

n the drawings, numerals ,10i andai ,designata draft eeanthis alato beinan contact with the.l

butt 0f` the coupler 2,6 Theirattgeen is ene brocoli` by` aol-tait rohe 2.1i which draityolref-is Connected to the @Qualen it in wellllr. c 4:.

The. draft: gear `allarmi-1a` Fiacre 1115s; a 1 houseine; generallyidesienated Matha is openlaoonet end andtis closed atitheiother'endfbyaa basewalli' 351,y thebasawall beingeoffset',toifrnms` an inwardlyi extendingzbossr I Nearf itsfopeni end; thenous ing 2 8f#` forms;P friction chamber providing# a 2 1 friction surface or surfaces 33; Preferably the friction chamber 32- is of longitudinal tapering congurationl the walls that provide" the friction surface 33 converging inwardly in longitudinal section as viewed in Figure 1. Rather than maire the friction chamber 32 circular incrossesection, 1 prefer'toremploy a polygonal coniiguration, the particular frictionk chamber shown in Figures l to cli-being hexagonal.

At the open end of the frictionchainber 3i? is a" follower orthr'ust member @5in Contact with the previously rnentioned follower plate 25. contemplated that the` thrust member 35` will have a convex inner face 362 in this instance, shaped as thesegment ofv a sphere. The convexity of the inner face is" required for a certainwedging effect, andthefspherical configuration is preferred to make the follower movable universallyl to conform automatically with changes in the angnlarity oi" the follower plate 25as the coupler 2t' swings to various angles relativeyto the longitudinalaxisof the car. The self'- aligning thrustl member 35, in maintaining con etant face-to-f'ace Contact with the follower plate"` 25, avoids, suchy wear as' would-be causedby relative movement" between the thrust member' and smaller'aperture 331 on its inner wall".

longitudinal restrainir'rgjrneansin the` form of an" axially positioned bolt` 40?" extending from the base wall Sti-of? the-draft gear casing tothe thrust mernbertt boitextendsthrough an aperture I inthe basewalboss 3l", with the headllzfoi the' bolt" ihsidethe boss; and at the other` end: the bolt extends' through the aperture 385 ofthethrust"meoiiber' the aperture 38" beiingsufliciently OVersiae-with respect to the bolt to perrni'ttl're required universal movement ofthe thru-sr mem-ber: Inside the thrust member- 35 a suitable temporary" washer 43; or lead or-other frangible niatra'l maybe mounted" on theboitI MJ" albngf'witlf a? permanent' meta'lwvasher d'5? the" two"waslier'sbei1ig`retained the usual nut @Si The purpose ortho" teniporaryiwasher btt'- hold@ the `draft gear initially in'hsufliciently" con tracted-state t'o pernflitI th'erdraft gear tot bein Immediately stalled in the draftgear pocket after irrstallatiorrA the" temporary washer is ruptured'b'yf loadi forces and drops "away to pere mitE the d'rattfg'ear toexr'ianditoltl'iei-full leifigtifi*` ofi thelpoclret.

draft gear of this inventian may take various forms, but I prefer to use the friction device disclosed in my prior Patent No. 2,496,442,- wherein the specific components and their coaction are described in detail. Since the instant application is a division of said Patent No. 2,496,442, reference characters found on the drawings of the instant application correspond with those of the earlier patent, and the specific parts therefore need not be described in detail here. Suffice it to say that the friction device comprises a plurality of friction shoes 41 which bear against the friction surface 33 of the friction chamber 32, and a plurality of wedge members 49 which distribute the buff and draft loads evenly over the friction shoes as these loads are imparted to the thrust member 35.

The present invention is particularly concerned with the spring means employed in conjunction with the friction device, and in the embodiment of the invention shown in Figures 1 to 5, inclusive, the spring means comprises a first relatively light spring 58 over which is telescoped a second relatively light preliminary travel spring ii which acts in tandem with a third spring 51 cf relatively heavy construction. A stepped follower 81, here shown as cup-shaped, comprises a disk portion 82 receiving the thrust of the outer ends of the inner spring 58 and the preliminary travel spring 80, and the follower has an outer iiange or rim portion 83 surrounding the preliminary spring portion 80. Between the free end of that rim portion 83 and the adjacent end of the outer spring 51, there is an inner spring seat or auxiliary follower 84 of suiiiicent depth to extend between the adjacent ends of the preliminary travel spring 80 and the outer spring 51 substantially as shown in Figures 1 and 4.

The disk portion 82 of the follower 8l is seated upon the friction device, in this case the frictionl shoes 41, and the rim portion 83 is normally spaced from the auxiliary follower 85 as indicated at 85 to permit preliminary travel of the draft gear while compressing the preliminary travel spring 80 and before effectively compressing the outer spring 51. For instance, in a high capacity draft gear having 2% inches total travel, the preliminary travel might be on the order of 3A 0f an inch.

This is illustrated in the diagram of Figure 6 in which the load deflection line 11 represents the load deflection characteristics of a high compression draft gear with the inches of travel of the gear being plotted as abscissas and the pounds of pressure as ordinates (the initial compression and corresponding effects being ignored). With the spring means employed in the instant invention, that curve is modified by introducing a preliminary travel corresponding to the line 18 followed by a further travel corresponding to the line 19 plotted in substantially the same way as 11. The effect of this is to permit a comparatively low resistance to preliminary travel-of the draft gear under a cornpression of applied load to soften the effect onv the car and reduce-the steepness of the loadv deiiection curve indicated by the line 11. Thereafter the travel is indicated by the line 19 and the result may be that the draft gear will have the same capacity if that is desired.

It will be understood that upon initial compression of the draft gear upon applied load, the inward movement or travel of the friction members 41 would be resisted by the preliminary travel spring 80 and the inner spring 58 acting in parallel during this preliminary travel of 3 inch, and the friction developed between the outer friction surfaces 5I of the wedge member t1 and the inner friction surfaces 33 of the friction chamber 32 would be relatively low as compared with a draft gear such as shown in Figures 1 to 5, inclusive, of my earlier Patent No. 2,496,442. Hence, there would be a preliminary travel having the characteristics of easiness or softness. At the end of that travel, the rim portion 83 of the follower 8! closes against the spring seat 8d, and further travel would -be resisted by the combined actions of the inner spring 58 and the relatively heavy spring 51 with the consequence that the friction between the wedge members 41 and the casing 28 would be enormously increased and the capacity of the `draft gear thus developed.

This manner of illustrating the improved preliminary travel feature of a high capacity draft gear is selected because of the minimum change required in conventional practice, but it is not intended to thereby impose an unnecessary limitation. Other forms will be readily designed.

This feature is a valuable accompaniment of the feature characterized by the novel thrust assembly which so readily collapses to rele-ase the parts upon release of the load, but it is also valuable in connection with other forms of high capacity draft gear.

I claim:

1. In a draft gear of the type including a. housing having a base wall and a side Wall, a portion of which side wall has an internal friction surface for coaction with a friction device mounted within said housing, the combination therewith of spring means interposed between the friction device and the base wall for resisting longitudinal movement of the friction device within the housing, said spring means comprising a first relatively light spring acting directly between the base wall and the friction device, second and third springs telescoped over the first spring and acting in tandem between said base wall and the friction device and in parallel with the first spring, said second spring being relatively light and the third spring relatively heavy, and means for de-activating the second spring after a predetermined preliminary travel of the gear, whereby the gear is characterized by soft action for said preliminary travel with the first and second relatively light springs taking substantially al1 of the load, and relatively stiff action after said preliminary travel with the first and third springs taking such load, said de-activating means including spaced followers, one bearing on the friction device and furnishing a seat for the rst and second springs, and the other acting as a bearing surface between juxtaposed ends of the second and third springs, and stop means on one of said followers for limiting movement of the followers toward each other after a given preliminary travel of the gear.

2. In a draft gear o f the type including a housing having a base wall and a side wall, a portion of which side wall has an internal friction surface for coaction with a friction device mounted within said housing, the combination therewith of spring means interposed between the friction device and the base wall for resisting longitudinal movement of the friction device within the housing, said spring means comprising a first relatively light spring acting directly between the base wall and the friction device,

second and third springs telescoped over the first.

5 spring and acting in tandem between said base wall and the friction device and in parallel with the first spring, said second spring being relatively light and the third spring relatively heavy, and means for dee-activating the' second spring after a predetermined preliminary travel of the gear, whereby the gear is characterized by soft action for said preliminary travel with the rst and second relatively light springs taking substantially all of the load, and relatively stiff action after said preliminary travel with the rst and third springs taking such load, said deactivating means including a cup-shaped follower resting on the friction device and internally receiving the rst and second spring, and a ledge on the follower spaced fromthe third spring when the gear is at rest and furnishing a seat therefor when the second spring has been compressed by an amount corresponding to said preliminary travel.

3. A draft gear as set forth in claim 2 in which a central locating bolt passes through the friction device, the spring means, and the base wall of the housing for holding the gear in assembled relation.

JAMES R. CARDTWELL.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,302,080 OConnor Apr. 29, i919 1,616,692 Haseltine Feb. 8, 1927 1,700,229 Lounsbury Jan. 29, 1929 2,458,572 Dentler Jan. 11, 1949 2,496,442 Cardwell Feb. 7, 1950 

